feat(reddit): implement Reddit scraping subagent and associated capabilities

- Added a new `reddit` subagent to scrape structured data from Reddit posts, comments, and users.
- Introduced `reddit.scrape` capability for fetching data using URLs and search queries.
- Implemented tools for scraping and parsing Reddit data, including handling pagination and rate limits.
- Created input/output models for the Reddit scraper to define request and response structures.
- Added documentation for the new Reddit scraping functionality and its usage.
- Integrated the Reddit subagent into the existing multi-agent chat framework.

surfsense_backend/app/capabilities/reddit/scrape/executor.py

@@ -0,0 +1,49 @@
+"""``reddit.scrape`` executor: verb input → scraper → Reddit items."""
+
+from __future__ import annotations
+
+from collections.abc import Awaitable, Callable
+
+from app.capabilities.core import Executor
+from app.capabilities.reddit.scrape.schemas import ScrapeInput, ScrapeOutput
+from app.exceptions import ForbiddenError
+from app.proprietary.platforms.reddit import (
+    RedditAccessBlockedError,
+    RedditScrapeInput,
+    scrape_reddit,
+)
+
+ScrapeFn = Callable[..., Awaitable[list[dict]]]
+
+
+def build_scrape_executor(scrape_fn: ScrapeFn | None = None) -> Executor:
+    """Bind the executor to a scraper fn (defaults to the proprietary actor)."""
+    scrape_fn = scrape_fn or scrape_reddit
+
+    async def execute(payload: ScrapeInput) -> ScrapeOutput:
+        actor_input = RedditScrapeInput(
+            startUrls=[{"url": url} for url in payload.urls],
+            searches=payload.search_queries,
+            searchCommunityName=payload.community,
+            sort=payload.sort,
+            time=payload.time_filter,
+            includeNSFW=payload.include_nsfw,
+            skipComments=payload.skip_comments,
+            maxItems=payload.max_items,
+            maxPostCount=payload.max_posts,
+            maxComments=payload.max_comments,
+            postDateLimit=payload.post_date_limit,
+            commentDateLimit=payload.comment_date_limit,
+        )
+        try:
+            items = await scrape_fn(actor_input, limit=payload.max_items)
+        except RedditAccessBlockedError as exc:
+            # Anonymous-only scraper; a hard block can't be retried with creds.
+            # Mirror google_maps' SignInRequiredError -> ForbiddenError mapping.
+            raise ForbiddenError(
+                f"Reddit refused anonymous access: {exc}",
+                code="REDDIT_ACCESS_BLOCKED",
+            ) from exc
+        return ScrapeOutput(items=items)
+
+    return execute